If you walk across the park afterwards to the west side, you could go to Cafe Ronda -- it's Argentinean-influenced tapas place, and while i've never had their paella and can't vouch for it, they do serve it...so i'd say keep it as a backup option if you should find yourself drifting west through the park after the museum and craving Spanish...

Otherwise, i'd recommend heading downtown...i like the paella at both La Nacional and Soccarat (sp?) very much...